Air-Purifying Respirators
Air-purifying respirators consist of a facepiece and an air-purifying device, which is either a removable component of the facepiece or an air-purifying apparatus worn on a body harness and attached to the facepiece by a corrugated breathing hose (see Figure 2 in section 4 of this module).
3M™ Half Facepiece Respirator 6000 Series Training Video
Air-purifying respirators selectively remove specific airborne contaminants (particulates, gases, vapors, fumes) from ambient air by filtration, absorption, adsorption, or chemical reactions. They are approved for use in atmospheres containing specific chemicals up to designated concentrations, and not for IDLH atmospheres.
Air-purifying respirators usually operate only in the negative-pressure mode except for powered air-purifying respirators (PAPRs) which maintain a positive facepiece pressure (except at maximal breathing rates). There are three types of air-purifying devices:
- particulate filters;
- cartridges and canisters, which contain sorbents for specific gases and vapors; and
- combination devices.
Their efficiencies vary considerably even for closely related materials.
Air-purifying respirators have limited use at hazardous waste sites and can be used only when the ambient atmosphere contains sufficient oxygen (19.5 percent) (30 CFR Part 11.90[a]). Conditions which may exclude the use of air-purifying respirators include:
- oxygen deficiency
- IDLH concentrations of specific substances
- entry into an unventilated or confined area where the exposure conditions have not been characterized
- presence or potential presence of unidentified contaminants
- contaminant concentrations are unknown or exceed designated maximum use concentration(s)
- identified gases or vapors have inadequate warning properties, the sorbent service life is not known, and the unit has no end-of-service-life (ESLI) indicator
- high relative humidity (may reduce the protection offered by the sorbent)
Knowledge Check Choose the best answer for the question.
1-11. What requirement must be met before you can use an air-purifying respirator?
You forgot to answer the question!